Peter Lewis / Snakes head fritillary (Fritillaria meleagris) flowering with Dandelions in meadow Cricklade, Wiltshire, England, UK, April.

Nigel Cattlin / Crown imperial (Fritillaria imperialis) flower head, close up.

Ernie Janes / Crown imperial (Fritillaria imperialis) growing in spring border, cultivated plant in garden.

Heather Angel / Snake's head fritillary (Fritillaria meleagris), view into flower with linear green nectaries. In cultivation, Surrey, England, UK. April.

Heather Angel / Crown imperial lily (Fritillaria imperialis), six nectaries at base of stamens and stigma. In cultivation, Native to southeast Turkey and western Himalayas.

Heather Angel / Wasp (Dolichovespula sp) emerging from nectaring on Michailovski fritillary (Fritillaria michailovskyi) flower. To reach the nectaries it squeezes past anthers picking up large pollen load on head and...

Mike Read / Snakeshead fritillary (Fritillaria meleagris) growing in garden lawn. Corfe Mullen, Dorset, England, UK. April.

Adrian Davies / Snakeshead fritillary (Fritillaria meleagris), rare double white variety. Beech Hill, Berkshire, England, UK. April.

Ingo Arndt / Chocolate Lily (Fritillaria camschatcencis) in flower, Lake Clark National Park, Alaska, June.

Chris Mattison / Snakeshead Fritillary (Fritillaria meleagris) Monmouthshire, Wales, UK. March.

Paul Harcourt Davies / Mountain fritillary (Fritillaria montana ) Mount Vettore. Umbria, Italy. June.

Paul Harcourt Davies / Fritillary flower (Fritillaria davisii) near Naufplio, Peloponnese, Greece, March.